Sometime past 10 p.m., on a dimly lit street north of Bucharest's Gara de Nord train station, a dozen prostitutes stake their ground in front of an abandoned building. When a van pulls up to the curb, a Roma teenager quickly puts out her cigarette, straightens her miniskirt, steps inside the vehicle and slams the door behind her. Ten minutes later, she emerges with a cheeky grin and shouts at the driver: "Merci, boss." But she doesn't walk away with a wad of cash. Instead, she's holding a bag of clean syringes.

Outreach workers from the Romanian Association Against AIDS (ARAS) make runs like this twice daily, distributing clean needles to Bucharest's most vulnerable residents: sex workers, street children and homeless adults, most of them Roma, and most of them heroin addicts. It's a vital service to help prevent the city's 17,000 addicts from sharing needles and spreading HIV. "Even the pimps know us now," says Alexandra Luca, a health educator in charge of this evening's run. "They see the women as money machines, so we explain that it's in their best interest to keep them healthy, clean and informed." (See pictures inside a Romanian drug house.)

With the global community focused on AIDS in Africa, Romania isn't an obvious front line in the fight against HIV. But across Eastern Europe and Central Asia, injecting drug use is driving the world's fastest-growing HIV epidemic. According to UNAIDS, since 2001, HIV prevalence in the region has risen by 66% to include 1.5 million people. In Russia, 160 people contract HIV every day and the average age of death from AIDS-related causes is just 32. An estimated 70% of Ukraine's injecting drug users (IDUs) now have HIV.

The problem, experts say, is lack of funding for HIV prevention and of political will to work with stigmatized groups. Despite the explosive growth of HIV rates in parts of Europe, UNICEF reports that combined international investment in HIV in the entire region of Eastern Europe and Central Asia "does not come close" to investments in a single country like Ethiopia, which records a similar number of HIV cases as Russia or Ukraine. "Donors and politicians see our region's epidemic as a lower priority," says Shona Schonning, an activist with the Eurasian Harm Reduction Network based in Vilnius, Lithuania. "They see the countries as a little richer and the epidemic as a little smaller, and therefore something that can be ignored. But the only difference between Eastern Europe and Africa is time." (See pictures of Africa's AIDS crisis.)

Until now, Romania had been the exception. Romanian NGOs were the first in the region to gear up AIDS-prevention programs targeting vulnerable groups a decade ago, and together they have helped keep the HIV rate among the nation's IDUs at just 1%  the lowest in Eastern Europe. That result is in big part thanks to needle-exchange programs run by ARAS and five other NGOs, who together gave out more than 1.6 million syringes last year to 7,500 addicts. Now a funding crisis could see all that good work undone. The NGOs have long relied exclusively on international donors. But nearly four years after Romania joined the European Union, the World Bank no longer classifies Romania as a developing country, making it ineligible for a number of international grants. Since June, UNICEF, the Open Society Institute and the Global Fund to Fight AIDS, Tuberculosis and Malaria have all withdrawn funding for the country's HIV programs. (See pictures: "Heroin's Global Reach.")

Without money going into prevention, some experts say, Romania's HIV problem could get very serious, very fast. "Where you don't provide interventions for drug injectors, there's a potential for the epidemic to rage out of control," says Martin Christopher Donoghoe, the World Health Organization project manager for HIV/AIDS in Europe. That has consequences for the rest of Europe too. Freedom of movement within the E.U. makes it easier for disease to spread; what's more, in 2008 Romania surpassed Russia to become the largest supplier of migrant sex workers to the E.U. "The bulk of HIV infections are in the east, but HIV doesn't respect national boundaries," says Donoghoe.